Lapping machines



May 16, 1961 c. T. CROFT 2,984,054 LAPPING MACHINES Filed May 19, 1959 3 Sheets-Sheet 1 Inventor Attorneys May 16, 1961 c. T. CROFT 2,984,054 LAPPING MACHINES Filed May 19, 1959 3 Sheets-Sheet 2 Alto. ey;

May 16, 1961 c. 'r. CROFT 2,984,054

LAPPING MACHINES Filed May 19, 1959 3 Sheets-Sheet 3 lv 49 58 1 v I 42 l l 4/ I 6 In venlor A ltorney s LAPPING MACHINES Charles T. Croft, Leigh-on-Sea, England, assignor to Dewrance & Co. Limited, London, England, a British company Filed May 19, 1959, Ser. No. 814,273

Claims priority, application Great Britain May 21, 1958 23 Claims. (Cl. 51-241) This invention relates to lapping machines and particularly to portable machines for lapping valve seatings. When the seating of a valve requires renovation the expense and inconvenience may be greatly increased by the necessity of disconnecting and removing the valve from the associated pipe-line or the like, particularly if the valve is installed by means of a welded joint or welded joints. It is very desirable therefore, to be able to lap the seatings of valves while the valves are in position and an object of the invention is the provision of a portable machine suitable for lapping fiat valve seatings.

In a portable machine for lapping a fiat valve seating, for example, the seating of a safety valve or stop valve, wherein a support member carrying a rotary member pro vided with driving means is adapted to be secured to the valve body at an opening thereof opposite the seating with the axis of rotation of the sleeve normal to the plane of the seating, a fluid pressure device having cylinder and piston elements is adapted to urge a lapping tool mounted on one of the elementsagainst the seating and one of the said elements is mounted eccentrically on a spindle itself eccentrically rotatably mounted on and extending parallel to the axis of rotation of the rotary member and provided with means whereby the spindle may be secured to the rotary member at selected angular positions to give dilferent eccentric movements to the lapping tool.

The invention will now be described, by way of example with reference to the accompanying partly diagrammatic drawings in which:

Figure 1 is a sectional side elevation of a lapping machine according to the invention mounted on a valve having a hat annular valve seat;

Figure :2 is a section on the line 2-2 of Figure 1, looking in the direction of the arrows, showing an eccentricity adjustment device;

Figure 3 is a front view partly from above of the lapping device of Figure 1 with part of the spindle and the fluid pressure supply means not shown; and I Figure 4 is a side view of the lapping device of Figure 1 and drive means therefor.

In Figure 1 a stop valve body 1 is formed with an annular member 2 presenting a fiat annular valve seat 3 at its upper end. A portable lapping machine 4 is mounted on the valve body 1 at an aperture 5 therein, with a movable lapping tool in the form of a disc 6 in contact with th valve seat 3.

- The lapping machine 4 includes a support member 7 comprising an annular plate 8 and a tubular part 9 welded to the annular plate 8 and registering with the central aperture of the annulus. The plate 8 is formed with a pair of diametrically aligned radial slots 10 as seen most clearly in Figure 3 for the passage of clamping bolts for clamping the plate to a valve body. Thus re spective bolts 11 pass through the slots 10 and into tapped holes providing threaded bores in the valve body 1. It will be appreciated that, in general, suitable threaded bores ,will be available on removal ofthe valve cover for ac- Srates Patent m ine cess to the seat to be lapped and that suitable slots such as the slots 10 are so positioned that bolts may be passed through the slots to register with threaded apertures over a range of valve sizes, for example the plate 8 may be provided with a plurality of pairs of slots of difierent radial lengths at varied angular and radial displacements.

The tubular member 9 is positioned normally with respect to the plate 8 and at its ends is formed with respective recesses in which L section annular bushes are seated. Thus at the upper end of the tubular member 9 an L section annular bush 1-2 is seated in an annular recess 13 formed in the member 9 with the branch of the L radially outwardly overlapping the upper end of the member 9 and presenting an upper bearing surface 14,

and with the stem of the L extending downwardly within the member 9 and presenting a radially inner bearing surface 15 radially inwards of the inner wall of the tubular member 9. At the lower end of the tubular member 9 an L section annular bush 16 is similarly seated in a recess .17 formed in the member 9 with the branch of the L overlapping the lower end of the tubular member and presenting a lower bearing surface 18, and the stem of the L extending upwardly within the recess 17 and presenting a radially inner bearing face 19 radially inwards of the inner wall of the tubular member 9.

An upright elongated cylindrical sleeve member 20 is rotatably mounted in the bushes 12 and 16, the sleeve member being slightly longer than the tubular member 9 and positioned with outer surface parts in sliding contact with the radially inner bearing surfaces 15 and 19. The lower end of the sleeve member 20 is closed as at 21 and is formed at the closed end with a radially outwardly projecting annular flange 22 which engages the lower bearing surface 18 of the adjacent bush 16 and serves to limit upward movement of the sleeve member 20 and resist upward thrust on the sleeve member 20.

At its upper end the sleeve member 20 is closed by a removable top cap 23 in the form of a circular plate of larger outer diameter than the sleeve member and provided with a threaded annular recess 24 in its lower face. The upper end of the sleeve member is threaded to engage in the threaded recess 24. The upper end of the sleeve member 20, below the top cap 23 is provided with a radially outwardly projecting annular worm wheel 25 which tightly embraces the sleeve member and is suitably prevented from rotation with respect to the sleeve mem her by locking means such as a key. At its upper side face the worm wheel 25 engages the top cap 23, and at its lower side face the worm wheel slidably engages the upper bearing surface 14 of the bush 12. The lower face of the worm wheel thus limits downward movement of the sleeve member 20 and serves to resist downward thrust on the sleeve member 20.

The arrangement is such that, when the top cap 23 is screwed down, the possible longitudinal movement of the sleeve member 20 is reduced, and the top cap is suitably so adjusted that there is minimum upward and downward movement consistent with free rotatability of the sleeve member 20 in the bushes 12 and 16.

The top cap 23 and the lower closed end 21 of the sleeve member are respectively formed with upright bores 26 and 27 of the same diameter which are arranged with their axes vertically aligned and spaced from the axis of rotation of the sleeve member 20. Thus the aligned axes of the bores 26 and 27 are spaced radially from and parallel to the axis of rotation of the sleeve 20.

An upright spindle 28, of annular cross section having an upright bore 28', extends through the bores 26 and 27. The outer diameter of the spindle is such that it is a push fitin the bores and may be rotated on application of sufficient torque. The spindle 28 is connected at its lower end to the flat upper end 29 of a cylinder 30, the cylinder being open at its lower end and, at its upper end, communicating with the inner passage 28' of the annular section spindle 28. The upper flat end 29 of the cylinder is normal .to the spindle 28 and the cylinder 30 is mounted eccentrically with respect to the spindle 28, the axes of the spindle 28 and the cylinder 36 being parallel and spaced apart.

The spindle 28 is adjustably secured to the rotatable sleeve by means whereby the spindle may be positioned at selected angular positions variously located in relation to the sleeve 20 to give different eccentric positions of the cylinder and consequently difierent eccentric movements of the lapping disc 6 as will be explained below.

Thus intermediate its ends the spindle 28 is formed with an outer threaded portion 31 on which is threaded a lock nut 32. The outer diameter of the threaded portion is the same as that of the lower part of the spindle extending through the sleeve member 20, but above the threaded portion the spindle 28 is of slightly reduced diameter to permit assembly of the lock nut 32 on the spindle 28. The threaded portion is so positioned that with the upper surface of the flat upper end 29 of the cylinder abutting the lower closed end 21 of the sleeve 20, the threaded portion extends upwardly from a level slightly below the upper end of the cap 23. The lock nut 32 is mounted on the spindle 28 above the top cap 23 of the sleeve member 20, and between the top cap 23 and the lock nut 32 an indicating pointer 33 is mounted on the spindle. As is seen more clearly in Figure 2, the indicator pointer is formed with an aperture closely embracing the spindle 2S and is locked as regards rotation relative to the spindle 28 by a small key 34. The indicator pointer is free to move, when the nut 32 is loosened, over a limited range vertically and registers with a scale marked on the upper surface of the top cap 23. Manual rotation of the pointer 33 over the scale 35 causes rotation of the spindle 28 relative to the sleeve member 29, and consequently rotation of the axis of the cylinder 30 about the spindle 28 and variation of the eccentricity of the axis of the cylinder 36 with respect to the axis of rotation of the sleeve member 20.

The cylinder 30 forms one element of a fluid pressure device, the other element of which is provided by a piston 36 slidably mounted within the cylinder 30 and provided with an annular recess 37 in its cylindrical peripheral surface in which is seated an O ring 38 for maintaining fluid tightness of the piston 36 in the cylinder 39 The piston 36 is formed with a lower cylindrical boss 39 coaxial with the cylinder 30 and threaded to engage with a complementary threaded recess 48 in the upper end of a readily removable upright rod or ram member 41. The lower end of the cylinder 30 is closed by a removable cylinder cap 42 which is retained on the cylinder 36 by cooperating threaded parts formed on the lower end of the cylinder and on the cap 42. The cylinder cap 42 is formed with a central circular aperature 43 of diameter sufii ient to permit free sliding of the rod 1 therethrough and with a suificiently small clearance between the rod 41 and the aperature 43 to inhibit the upward passage of deleterious matter such as dust into the cylinder 39 and olfer lateral support to the rod 41.

At its lower end the rod 43 is connected to the circular lapping disc 6 by means of a screw 44 passing upwardly through a central aperture 45 in the lapping disc and engaging with an upright threaded aperture 46 in the lower end of the rod 41. The control 45 is counter sunk at the lower face of the disc 6 so that the head of the screw 44 is above the lower surface of the disc 6, at the upper face of the disc the aperture is enlarged into a concavity forming part of a spherical surface and adapted to engage the lower end of the rod 41 which is formed with a complementary convex surface forming part of a spherical surface. So that the lapping disc may execute a limited rocking movement with respect to the rod 41 with sliding between the concavity in the disc 6 and the curved lower end of the rod 41 the aperture is of larger diameter than screw 44 and the threaded aperture 46 is of such depth that with the screw 44 home to the upper end of the recess, disc 6 is not clamped tightly by the head of the screw 44.

The lapping disc 6 is suitably formed in well known manner with shallow grooves on its lower face to retain lapping paste.

The spindle 28 is closed at its upper end which is reduced in diameter to provide a shoulder 47, and a radial bore 48 is formed to communicate with the inner bore of the spindle above the shoulder 47. A banjo type coupling 49 is clamped on to the upper end of the spindle 28 and against the shoulder 47 by means of a clamping nut 50 cooperating with an upper threaded end portion 51 of the spindle 28. The banjo coupling 49 comprises a banjo shaped body 52 which is formed with an upright bore 53 slidably fitting the upper end part of the spindle below the threaded end portion 51, and is formed with a transverse bore 54 extending outwardly from one side of the upright bore 53. The body 52 is formed internally with an annular recess 55 communicating with the transverse bore 54 and circumscribing the upright bore 53 at a level corresponding to that of the radial bore 48 in the spindle 23. Thus with the banjo coupling 49 held in position by the nut 50, the radial bore 48 is necessarily in communication with the annular recess 55, so that the internal bore 28 of the spindle 28 is in com munication with the transverse bore 54 of the banjo coupling 49.

The thickness of the banjo coupling 49 is such that'with the nut 50 screwed to the limit of its downward travel the spindle 28 is free to rotate in the banjo coupling 49 and clearances between the shoulder 47 and the lower face of the banjo coupling 49 between the lower face of the nut 50 and the upper face of the banjo coupling 49, and between the upright bore 53 through the banjo coupling and the spindle 28 are as small as possible as is consistent with free rotation of the spindle 28 relative to the banjo coupling 49 to inhibit the escape of pressure fluid, and the banjo coupling 49 is provided internally in the bore 53 with fluid pressure sealing means comprising upper and lower 0 rings 56 and 57 respectively above and below the annular recess 55.

The banjo coupling 49 is connected in fluid tight manner to a flexible pipe or tube 58 which communicates at one end with the transverse bore 54 and at its other end is connected to one side of a manually operated fluid pressure control valve 59 the other side of which is connected to a source 60 of fluid under pressure. For example, the source 60 comprises a compressed air bottle and the valve 59 is adatped to supply air at a suitable pressure through the bore 28' of the spindle 28, to the cylinder 30 above the piston 36. A suitable operating pressure in the cylinder 30 is a pressure of the order of 10 lb. per square inch above atmospheric pressure, but of course, will depend on the size of the valve seat and the size of the piston in any particular case.

Below the banjo coupling 49 the spindle 28 is provided with a fluid pressure relief valve 67 comprising a screw 68 having an axial bore 69 open at the outer end of the screw 68 and at the inner end communicating with an inclined passage 69 opening in a tapered inner end part 70 of the screw. The screw is arranged in a threaded recess having a complementary tapered inner end opening inwardly to the spindle bore 28'. By adjustment of the screw 68 the tapered end portion of the screw may cooperate with the tapered part of the aperture and close the passage through the screw to prevent the escape of fluid from the passage 28 outwardly through the screw. If the screw is adjusted outwardly from this position, a controlled leak of pressure fluid from the passageway 28' may be obtained and the fluid pressure in the cylinder 30 thereby relieved when it is desired to release pressure on the lapping disc 6. It will be understood that in these circumstances the supply of pressure fluid from the source 60 will be cut off by adjustment of the pressure reducing valve 59 or a stop valve associated with the supply 60.

Operation of the machine is efiected through a worm 61 supported for rotation in a cylindrical casing 62 which is rigidly attached to the upper end of the tubular member 9. The cylindrical casing 62 is open adjacent the worm wheel 25 to permit driving engagement of the worm 61 with the worm wheel 25. At one end the worm is formed with a rectangular slot 63 and at this end the casing 62 is open to permit insertion of a driving key 64 into the slot and rotation of the key to cause rotation of the worm 61. The key 64 is suitably held in the chuck 65 of an electric or pneumatic drill 66, as shown in Figure 4, which in operation causes rotation of the key 64, and consequent rotation of the worm 61. Alternatively the key 61 may be manually driven from a hand operated drill.

In operation, when it is desired to lap a flat valve seat such as the seat 3 of Figure 1, the valve cover and associated parts are removed and the depth from the opening in the valve body to the valve seat is measured. A rod orthrust member 41 is selected of appropriate length to ensure desired engagement between the lapping disc 6 and the valve seating when the plate 8 is bolted in position on the valve body and the piston element 36 of the cylinder 30 is in an intermediate position in the cylinder 30. The selected rod 41 is screwed on to the boss 39 at the lower side of the piston 36 and the lapping disc 6 is attached to the lower end of the rod 46 by means of the screw 44.

Abrasive compound is applied to the lower face of the lapping disc 6, the coarseness of the grit in the compound being selected in view of the condition of the valve seat,

the completion of the lapping operation always being effected by use of a compound comprising very fine grit. The lapping machine 4 is mounted in position on the valve body by means of bolts 11, and the nut 32 is loosened. The indicator pointer 33 is adjusted until it is in a position to allow maximum movement of the lapping disc 6 on rotation of the sleeve 20 without interference between the disc 6 and the valve body or uncovering part of the valve seat. At this position the nut 31 is tightened, locking the cylinder 30 in position with respect to the rotatable sleeve 20.

The valve 59 is adjusted to permit fluid under pressure into the cylinder 30 above the piston 36 by way of passages 54 and 28', thus urging the piston downwardly and the disc 6 downwardly against the valve seat 3.

The worm 61 is rotated under the influence of the drill device 66 causing the worm wheel 61 to rotate and drive the wheel 25 and cause the sleeve 20 to rotate in its bearings 12 and 16. The disc 6 execute a rotary motion about the axis of the sleeve 20 and effects lapping of the valve seat. After a suitable interval, fluid pressure is relieved and the machine is removed, the disc 6 is cleaned and applied with lapping compound having a finer constituent grit and the operation repeated. The operation may be carried out in several stages using successively finer grits until the valve seat is lapped to a desired condition. The lapping of thevalve seat maybe carried out Whilst the valve body is in its operational position and whatever the position or angle of installation of the valve.

I claim:

1. A portable lapping machine for lapping a flat valve seating within a valve body formed with an aperture opposite said seating, comprising a support member adapted to be secured to the valve body at said opening, a rotatable member rotatably mounted on the support member, driving means for efiecting rotation of the rotatable member, a spindle rotatably mounted on the rotatable member with its axis of rotation parallel to but displaced'sidewardly in relation to the axis of rotation of the rotatable member, a lapping tool positioning means including a fluid pressure device having cylinder and piston elements one of which is mounted eccentrically on the spindle with the axis of the elements parallel to the axis of rotation of the spindle, the cylinder element enclosing a space at a side of the piston element, a fluid flow duct leading to said space at the side of the piston element and clamping means for securing the spindle at selected angular positions in relation to the rotatable member to vary the eccentricity of the lapping tool relative to the rotatable member.

2. A machine as claimed in claim 1, wherein the rotatable member is in the form of an elongated cylindrical sleeve rotatably mounted in bearings at opposite ends of the sleeve adapted to limit longitudinal movement of the sleeve.

3. A machine as claimed in claim 1, wherein the means whereby the spindle may be secured to the rotary member at selected angular positions comprises a positioning member fixed as regards rotation to the spindle and lockable in selected angular position to the rotary member.

4.A machine as claimed in claim 1, wherein the spindle is hollow and serves for the supply of pressure fluid to the fluid pressure device.

5. A machine as claimed in claim 4, wherein the spindle is provided with an adjustable fluid pressure relief valve for relieving the pressure of fluid in the fluid pressure device. 6. A machine as claimed in claim 4, wherein a coupling member adapted to be connected to a source for the supply of pressure fluid is formed with a bore in which the spindle is rotatably positioned, the spindle being formed with an inlet for pressure fluid communi eating with an annular recess formed in the bore and connected to the source, the recess being arranged so as to communicate with the aperture at all rotational positions of the spindle.

7. A portable lapping machine for lapping a flat valve seating within a valve body formed with an aperture opposite said seating, comprising a support member adapted to be secured to the valve body at said opening, a rotatable member rotatably mounted on the support member, driving means for effecting rotation of the rotatable member, a spindle rotatably mounted on the rotatable member with its axis of rotation parallel to but displaced sidewardly in relation to the axis of rotation of the rotatable member; lapping tool positioning means including a fluid pressure device having cylinder and piston elements one of which elements is connected to one end of a readily removable ram member formed at its other end with means for connection to a lapping tool, the other of which elements is mounted eccentrically on the spindle with the axis of the elements parallel to the axis of rotation of the spindle, the cylinder element enclosing a space at a side of the piston element, a fluid flow duct leading to said space at the side of the piston element, and clamping means for securing the spindle at' selected angular positions in relation to the rotatable member to vary the eccentricity of the lapping tool relative to the rotatable member.

8. A machine as claimed in claim 7, wherein the rotatable member is in the form of an elongated cylindrical sleeve rotatably mounted in bearings at opposite ends of the sleeve adapted to limit longitudinal movement of the sleeve.

9. A machine as claimed in claim 7, wherein the spindle is hollowand serves for the supply of pressure fluid to the fluid presure device.

10. A machine as claimed in claim 9, wherein the spindle is provided with an adjustable fluid pressure rclief valve for relieving the pressure of fluid in the fluid pressure device.

11. A machine as claimed. in claim 9, wherein a coupling member adapted to be connected to a source for the supply of pressure fluid is .formed with a bore in which the spindle is rotatably positioned, the spindle being formed with an inlet for pressure fluid communicating with an annular recess formed in the bore and connected to the source, the recess being arranged so as to communicate with the aperture at all rotational positions of the spindle.

12. A machine as claimed in claim 7, wherein the means whereby the spindle may be secured to the rotary member at selected angular positions comprises a positioning member fixed as regards rotation to the spindle and lockable in selected angular positions to the rotary member.

13. A portable lapping machine for lapping a fiat valve seating within a valve body formed with an aperture opposite said seating, comprisinga support member adapted to be secured to the valve body at said opening, a rotatable member rotatably mounted on the support member, driving means for effecting rotation of the rotatable member, a spindle rotatably mounted on the rotatable member with its axis of rotation parallel to but displaced sidewardly in relation to the axis of rotation. of the rotatable member, a lapping tool positioning means including a fluid pressure device having cylinder and piston elements one of which is mounted eccentrically on the spindle with the axis of the elements parallel to the axis of rotation of the spindle, the cylinder element enclosing a space at a side of the piston element, a fluid flow duct leading to said space at the side of the piston element, and the other of which elements is connected to a lapping tool by means including a ram member, means connecting the ram member to the tool being adapted to permit relative limited rocking in all directions between the ram member and the tool, and clamping means for securing the spindle at selected angular positions in relation to the rotatable member to vary the eccentricity of the lapping tool relative to the rotatable member.

14. A machine as claimed in claim 13, wherein an end of the ram member adjacent the tool is formed with a convex surface forming part of a spherical surface and the tool is formed adjacent the rod with a complementary concavity in the form of part of a spherical surface, the tool being attached to the rod by means permitting limited relative sliding between the part spherical surfaces.

15. A machine as claimed in claim 13, wherein the spindle is hollow and serves for the supply of pressure fluid to the fluid pressure device.

16. A machine as claimed in claim 15, wherein the spindle is provided with an adjustable fluid pressure relief valve for relieving the pressure of fluid in the fluid pressure device.

17. A machine as claimed in claim 15, wherein a coupling member adapted to be connected to a source for the supply of pressure fluid is formed with a bore in which the spindle is rotatably positioned, the spindle being formed with an inlet for pressure fluid communicating with an annular recess formed in the bore and connected to the source, the recess being arranged so as to communicate with the aperture at all rotational positions of the spindle.

18. A machine as claimed in claim 13, wherein the rotatable member is in the form of an elongated cylindrical sleeve rotatably mounted in bearings at opposite ends of the sleeve adapted to limit longitudinal movement of the sleeve. 7

19. A machine as claimed in claim 13, wherein the means whereby the spindle may be secured to the rotary member at selected angular positions comprises a positioning member fixed as regards rotation to the spindle and lockable in selected angular positions to the rotary member.

20. A portable lapping machine for lapping a flat valve seating within a valve body formed with an aperture opposite said seating, comprising a support member adapted to be secured to the valve body at said opening, a rotatable member rotatably mounted on the support member, driving means for effecting rotation of the rotatable member, a hollow spindle rotatably mounted on the rotatable member with its axis of rotation parallel to but displaced sidewardly in relation to the axis of rotation of the rotatable member, a lapping tool positioning means including a fluid pressure device having cylinder and piston elements one of which is mounted eccentrically on the spindle with the axis of the elements parallel to the axis of rotation of the spindle, the cylinder element enclosing a space at a side of the piston element, a fluid flow duct provided by said hollow spindle leading to said space at the side of the piston element, clamping means for securing the spindle at selected angular positions in relation to the rotatable member to vary the eccentricity of the lapping tool relative to the rotatable member.

21. A machine as claimed in claim 20, wherein a coupling member adapted to be connected to a source for the supply of pressure fluid is formed with a bore in which the spindle is rotatably positioned, the spindle being formed with an inlet for pressure fluid communicating with an annular recess formed in the bore and connected to the source, the recess being arranged so as to communicate with the aperture at all rotational positions of the spindle.

22. A machine as claimed in claim 21, wherein the spindle is provided with an adjustable fluid pressure relief valve for relieving the pressure of fluid in the fluid pressure device.

23. A machine as claimed in claim 22, wherein the means whereby the spindle may be secured to the rotary member at selected angular positions comprises a positioning member fixed as regards rotation to the spindle and lockable in selected angular positions to the rotary member.

References Cited in the file of this patent UNITED STATES PATENTS 2,292,383 Liebmann Aug. 11, 1942 2,303,531 Eyster Dec. 1, 1942 2,418,840 Karweit Apr. 15, 1947 2,600,815 Turner June 17, 1952 FOREIGN PATENTS 69,974 Sweden May 10, 1928 

